变复数
问题描述：
变复数
1.This is a knife
2.That is an apple tree
3.He is a policeman
4.The ruler is mine
5.What is his name?
6.There is a sheep on the hice?
7.Who is that man?
答
thoes are knives.
those are apple trees.
they are policemen.
the rulers are mine.
what are their names、
there are sheep on the hice.
who are those men?